Wire up an api to darken screen for accessibility

chrome/browser/resources/chromeos/chromevox/cvox2/background/command_handler.js

Index: chrome/browser/resources/chromeos/chromevox/cvox2/background/command_handler.js
diff --git a/chrome/browser/resources/chromeos/chromevox/cvox2/background/command_handler.js b/chrome/browser/resources/chromeos/chromevox/cvox2/background/command_handler.js
index f37c37318f0dc822ea013835bc0c7c5e487a6a26..09fd6d6c0366917adfd4bf598e4d212a0116fa5e 100644
--- a/chrome/browser/resources/chromeos/chromevox/cvox2/background/command_handler.js
+++ b/chrome/browser/resources/chromeos/chromevox/cvox2/background/command_handler.js
@@ -192,6 +192,20 @@ CommandHandler.onCommand = function(command) {
     case 'showNextUpdatePage':
       (new PanelCommand(PanelCommandType.UPDATE_NOTES)).send();
       return false;
+    case 'darkenScreen':
+      // Called twice to ensure the cros end of the dbus message is in a good

[dmazzoni, 2017/03/24 16:02:40]

I just think that detail should be handled lower down
the stack. Just call chrome.accessibilityPrivate.darkenScreen
once here, and then have accessibility_extension_api.cc call
it twice if necessary, with the comment here.

[David Tseng, 2017/03/24 18:07:43]

Ok, I see this as a one off api, so fine either way though this will make
debugging a little harder at runtime.

+      // state.
+      chrome.accessibilityPrivate.darkenScreen(false);
+      chrome.accessibilityPrivate.darkenScreen(true);
+      new Output().format('@darken_screen').go();
+      break;
+    case 'undarkenScreen':
+      // Called twice to ensure the cros end of the dbus message is in a good
+      // state.
+      chrome.accessibilityPrivate.darkenScreen(true);
+      chrome.accessibilityPrivate.darkenScreen(false);
+      new Output().format('@undarken_screen').go();
+      break;
     default:
       break;
   }